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E. CROFT. MACHINE FOR MAKING SCREWS.

Patented July 9, 1867.

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EDWARD CROFT, OF WATERBURY, CONNECTICUT. Letters Patent No. 66,568, datedJuly 9, 1867.

IMPROVED MACHINE FOR. MAKING SCREWS.

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TO ALL WHOM IT MAY CONCERN:

Be it known that L'EDWARD CROFT, of Waterbury, New Haven county, Connecticut, have invented, made, and applied to use a new and useful Machine for Forming the Threads of Screws and Knurling the Heads of the same; and I do declare the following to be a full, clear, and exact description of the same, reference being'had to the accompanying drawings, making part of this specification, and to theletters of reference marked thereon, in which- Figure 1, a side elevation of my improved machine.

Figure 2, a top view of the same.

Figure 3, a cross-section of the same.

Figure 4, a section lengthwise of the same.

In the drawings, like parts of this invention are indicated by the same letters of reference.

The nature of my invention consists in the construction and operation of an improved machine for forming the threads upon screws and knurling the heads of the same, as more fully hereinafter set forth.

To enable those skilled in the art to make and use my invention, I will proceed to describe the same.

A shows the frame for supporting the operating parts of my improved machine, and B is a shaft passing through the table of said frame and stepped at b. Upon the top of the shaft B is secured the circular die 0, upon the periphery of which are formed threads corresponding to the threads required upon the screw, and ofa suitable pitch to form the same. D is a stationary die secured to the table of the frame A; this die is threaded to correspond with the die G, and when placed in the position it occupies, its inner surface forms the segment of a'circle"nearlylparallelto the inner surface of the die 0. E shows a second circular die secured upon the shaft B, the periphery of which is provided with a knurl suitable to form the knurl on the head of the screw; F is a corresponding knurling die securedto'the table of the frame A.

My improved machine being thus constructed its operation is as follows: A pulley may be placed upon the shaft B, which is connected to any convenient motor, and the shaft B is thus set in motion. When the same has reached the proper position the blank on which the thread is to be formed is fed in between the dies D and C and is allowed to roll between them, the thread upon the same being formed as the blank passes between the dies.

After the thread has been fully formed upon the blank, the threaded blank is taken by the knurling dies in the same manner and knobbed. The die C, which is shown as entirely round, may be made partially so if desired- 1 do not wish to be understood as intending to claim any of the-devices patented by Cullen Whipple in 1852, and therefore distinctly disclaim said devices.

Having thus described my invention, what I claimns new, and'desire-to secure by Letters Patent, is-

1. I claim the revolving and stationary threading diesi'whon the same shall be constructed and combined, 'substantially as shown for the purposes specified.

2. In combination with the revolving and stnticharyf'dics C Dlc laim thelknobbing dies, when the same shall he construct'ed and operate substantially as shownv for the pn'rposes'set forth.

EDWARD CROFT. Witnesses:

WILLIAM GILLETTE, Guns. N. GILLETTE. 

